Astaxanthin and canthaxanthin are dye compounds widely distributed in microbial cells, macroalgae, and miroalgae, and in various animals and plants. The compounds are used as aging retarders, detoxificants, cancer preventive agents and color improving agents of bred fish.
While astaxanthin among the natural carotenoids has been extracted from shells of crustaceans, the content of the compound in the body of these animals is quite low and extraction of the compound is very difficult. Moreover, the crustaceans are bio-resources inhabiting in limited areas of the oceans with difficulties for ensuring stable supply thereof, these resources are not suitable for industrial production.
While astaxanthin is produced by a red yeast Phaffia rhodozyma, growth rate of this yeast is slow and productivity of astaxanthin is small. Moreover, since the yeast has a tough cell wall, extraction of produced astaxanthin is difficult. In addition, since the content of a (3R, 3R′) isomer having a chemical structure with an orientation reverse to that of natural astaxanthin is high, productivity of astaxanthin becomes inevitably low.
Haematococcus pluvialis are also known to produce astaxanthin. However, since the growth rate of this alga is low with a tough cell wall, productivity of astaxanthin is also low. In addition, since growth of the alga is variously restricted such that the alga is readily contaminated with bacteria, and is required to be cultured under irradiation of intense light using a special culturing apparatus, industrial production of astaxanthin involves many problems.
Canthaxanthin is distributed in a certain kind of mushroom, fish and crustacean, and are known to be produced by microorganisms belonging to genus Brevibacterium and genus Rhodococcus. While methods for obtaining canthaxanthin by chemical synthesis has been developed, the methods are not industrially used due to their low productivity.